PPTP Errors 651 and 800

[Renato Maia]

Hi all,

I have a home network (D-Link 624 Router and an Internet cable connection).
There is a desktop computer and occasionally I use my work laptop on this
network. Both are Windows XP Pro with SP2. Both have ZoneAlarm Pro installed
and Windows Firewall disabled.

I used to connect to my company's VPN server (Microsoft's VPN client using
PPTP) from the desktop computer without a problem (for more than 1 year).
After a minor ZoneAlarm Pro upgrade (it seems to be the only signficant
change that took place) my desktop VPN connection started to fail with Error
800. I decided to remove ZoneAlarm and kept Windows Firewall disabled. The
problem persisted. I suspected the problem might be related to D-Link
router. Upgrade its firmware version and the problem continued to happen.
Tried to connect my desktop computer directly to the cable modem and I still
get the same error (Although I was able to establish the VPN using IPSec and
a Pre-shared key which is not possible behind the router due to NAT issues
with IPSec). If I change the VPN type property from Automatic to PPTP the
error change to Error 651 (Modem has reported an error).

The weirdest thing is that I can establish the same PPTP VPN connection from
my notebook (XP SP2, behind the same D-Link router, running Zonealarm Pro).

Has anyone seen anything like this ?

An Ethereal trace captured on the desktop computer shows that it can contact
my VPN Server (Microsoft Windows 2003 RRAS on an ISA 2000 Server), establish
the TCP connection (port 1723), exchange a couple of PPTP messages and then
stops (closes the connection with a sequence of FINs and RST packets).

Renato Maia
Brazil

 

[Renato Maia]

It seems to be something related to my desktop operating system. I tried to
establish a VPN connection between
the desktop and my notebook. They are on the same LAN. The same behavior
happened.

The packet trace is like this :

Desktop -> Syn -> Vpn Server
VPN Server -> Syn/Ack -> Desktop
Desktop -> PPTP Start-Control-Connection-Reply -> VPN Server
VPN Server -> PPTP Start-Control-Connection-Request -> Desktop

Desktop -> Ack -> VPN Server (this one completes the TCP 3 way handshake. I
thought there might be a problem because it was completed (3-way handshake)
after a couple of other packets, but this happens when I successfully
connect using the notebook. It is probably a performance thing.)

(there is a "big" delay(something like 15-20 seconds) and then this sequence
happens)

Desktop -> Fin/Ack -> VPN Server
VPN Server -> Fin/Ack -> Desktop
Desktop -> Ack -> VPN Server
Desktop -> RST/Ack -> VPN Server

Please, help me !!!

Renato